@MaP Sorry for the late reply, for some reason I'm not receiving notifications...
Yes, thermal shutdown can definitely be a faulty fan. that and how the unit is stored.
They are usually the leading causes of the ES units failing (maybe IO as well?)
Get yourself a replacement if you can, they're usually around $5 USD mark...
A dead give away is the noise of the bearings in the fan itself.
Also how is the unit stored? is it in an open air case or is it sealed with an IP rated box that gets really muggy.
I do know the ED units are prone to overheating, but they have a guts load more kick than the GT's spineless raspberry pi 3
Fox